What Is a Heart Murmur, and Should You Be Worried?

In this guide

Rewritten from source material originally published at: prestigeanimalhospital.com (What is a Heart Murmur)

During a routine visit, your vet will listen to your dog or cat's heart with a stethoscope. A normal heartbeat has a steady, predictable rhythm; a heart murmur breaks that pattern, either with an extra beat or with a distinctive 'whooshing' sound layered over the normal rhythm.

An irregular heartbeat or unusual sound like this can indicate a heart murmur, but it is worth not jumping straight to worry. Murmurs come in many forms, some pets are born with them, others develop them over time, and in either case, catching one early generally means it can be managed effectively. Once a vet identifies a murmur, the next step is usually looking for other symptoms that help pin down what is behind it.

The three types of heart murmur

Murmurs are classified by when they occur during the heartbeat:

• Systolic, occurring as the heart contracts
• Diastolic, occurring between beats
• Continuous, present throughout the cycle

Once a vet detects a murmur, they will listen more closely to place it into one of these categories and often grade its loudness. Some murmurs are so faint they are only audible through a stethoscope, while others are noticeable even without one.

What else matters?

Beyond timing and volume, where the murmur is loudest also matters, and combined with a pet's age and general health, this location can offer useful clues. In older dogs, for instance, a murmur centred low on the left side of the chest can point toward degenerative mitral valve disease, while a murmur audible in the neck can suggest aortic stenosis. Because murmurs can involve unusual vibrations, disrupted blood flow, or even blockages, pinpointing the exact cause from sound alone is not straightforward, and location and loudness are only part of the picture; age and any accompanying symptoms matter just as much.

Puppies are sometimes born with a murmur that resolves on its own within the first few months of life; this is described as congenital. Other pets develop a murmur later in life as heart disease progresses, referred to as an acquired murmur.

How are heart murmurs treated?

There is no treatment that addresses a murmur directly. Instead, any treatment targets the underlying condition and symptoms behind it. Vets sometimes recommend chest x-rays to get a clearer picture of the heart's condition, but the approach really does depend on the individual case.

Are some breeds more prone to heart murmurs?

Certain breeds do carry a higher risk. King Charles Cavalier Spaniels and toy poodles are prone to degenerative mitral valve disease, which enlarges the heart as blood flows backward and can lead to coughing and reduced interest in exercise. Dachshunds are prone to leaky valves, usually manageable with medication and weight control. Larger breeds are not exempt either, boxers and golden retrievers carry their own risk, and among cats, Maine Coons, Siamese, and Persians can be prone to a condition called hypertrophic cardiomyopathy.

Because there is no single treatment for heart murmurs as a category, your vet will build an individual plan around your pet's specific diagnosis. Regular veterinary visits matter here: an annual wellness check is generally recommended up to around five years of age, moving to twice yearly after that, since pets age considerably faster than people and a lot can change in just six months.

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